The MIMO (Multi-Input Multi-Output) technique which simultaneously utilizes a plurality of frequency bands has been put into use so as to provide a communication with a higher speed and a larger capacity in mobile communicating equipment which is represented by a smart phone or a tablet. Since each frequency band needs a RF component, if the frequency bands for communication are increased in number, in order to maintain the original size of the equipment where increased components are disposed, each component needs to be further downsized and provided with more functions.
Such an electronic component working at a high frequency can be, for example, a diplexer, a band-pass filter or the like. All of these components contain the combination of dielectric material(s) functioning as capacitor and magnetic material(s) functioning as inductor. In order to provide good high-frequency characteristics, each kinds of loss at a high-frequency region are required to be suppressed.
The requirements for the dielectric material are as follows. (1) According to the requirements for downsizing, the relative permittivity (∈r) is required to be high in order to decrease the area of the capacitor. (2) The dielectric loss is required to be low, i.e., the Q value is required to be high in order to obtain a good selectivity in frequencies. (3) The breakdown voltage is required to be high.
For example, generally speaking, the Q value of the amorphous film of SiNx under a high frequency (2 GHz) is as high as about 500, and the breakdown voltage is as high as about 500 to 700 V/μm, thus, it can be widely used in the electronic components using under the high frequency. However, its relative permittivity (∈r) is as low as about 7, so a large area is needed to provide the target functions. In this respect, it is hard to meet the downsizing requirements.
In Non-Patent Document 1, in the CaZrO3 film, a Ca—Zr—O amorphous film is formed by providing an annealing process after the film deposition. At this time, it is reported that the relative permittivity at 100 kHz of the Ca—Zr—O amorphous film is 12.8˜16.0, and the Q value is 370 to 555.
Non-Patent Document
Non-Patent Document 1: Science direct Physica B, 348(2004) 440-445, Preparation and characterization of sol-gel derived CaZrO3 dielectric thin film for high-k applications.